[Spice-devel] [PATCH] spice-vmc: split vmc_write to max sized virtio_serial_write calls

[Arnon Gilboa]

Alon Levy wrote:
> This is required for working agent in windows guests with up coming release. Prevents pretty blue screens. Please Ack.
>
> workaround for current windows driver limitation (RHBZ 617000)
> ---
>  hw/spice-vmc.c |   21 ++++++++++++++++++---
>  1 files changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/hw/spice-vmc.c b/hw/spice-vmc.c
> index 8e14446..bf0c06e 100644
> --- a/hw/spice-vmc.c
> +++ b/hw/spice-vmc.c
> @@ -21,6 +21,8 @@
>  #define VMC_GUEST_DEVICE_NAME "com.redhat.spice.0"
>  #define VMC_DEVICE_NAME       "spicevmc"
>  
> +#define VMC_MAX_HOST_WRITE    2048
> +
>  #define dprintf(_svc, _level, _fmt, ...)                                \
>      do {                                                                \
>          static unsigned __dprintf_counter = 0;                          \
> @@ -43,10 +45,23 @@ typedef struct SpiceVirtualChannel {
>  static int vmc_write(SpiceVDIPortInstance *sin, const uint8_t *buf, int len)
>  {
>      SpiceVirtualChannel *svc = container_of(sin, SpiceVirtualChannel, sin);
> -    ssize_t out;
> +    ssize_t out = 0;
> +    ssize_t last_out;
> +    uint8_t* p = (uint8_t*)buf;
> +
> +    while (len > 0) {
> +        last_out = virtio_serial_write(&svc->port, p,
> +                            MIN(len, VMC_MAX_HOST_WRITE));
> +        if (last_out > 0) {
> +            out += last_out;
> +            len -= last_out;
> +            p += last_out;
> +        } else {
> +            break;
> +        }
> +    }
>  
> -    out = virtio_serial_write(&svc->port, buf, len);
> -    dprintf(svc, 3, "%s: %lu/%d\n", __func__, out, len);
> +    dprintf(svc, 3, "%s: %lu/%zd\n", __func__, out, len + out);
>      return out;
>  }
>  
>   
ACK